Lpc2000

----- Original Message ----- 
From: "martymcflap" <martinjp@...>
To: <lpc2000@yahoogroups.com>
Sent: Thursday, February 16, 2006 9:24 AM
Subject: [lpc2000] LPC210X P0.17 and P0.18 Operation.


> I'm using the 48 pin LPC2102 and I'm having difficulty configuring 
> P0.17 and P0.18. I want to use these pins as a general purpose 
> output to provide a high and low voltage without any pull ups, the 
> problem is that on the board I'm using these pins appear only to be 
> able to give me an open drain output. 
> 
>>From the Pin Configuration section (Chapter 6) of the User Manual 
> both P0.17 and P0.18 are indicated to be "5v tolerant pad providing 
> digital I/O functions with TTL levels and hysteresis and 10ns Slew 
> rate control" so it would seem that these pins can provide the 
> required output. Now although I'm configuring the pins as GPIO I 
> realise that these pins are shared with the I2C functionality, 
> however for the other pins which can share both GPIO and I2C (P0.2 
> and P0.3) it is explicitly stated in the manual that they are "open-
> drain 5 V tolerant digital I/O I2C-bus 400Khz specification pad, it 
> requires external pull-up to provide an Output functionality"
> 
> Is the manual wrong?, have I misunderstood? or do I need to 
> configure something apart from the PINSEL0/PINSEL1? Any Ideas?

IIRC, they need pull-ups on the LPC2106. The LPC2102 is probably the same.

Leon